In a constant undertaking towards the replacement of costly natural materials or the reproduction of original fragrance notes, the perfume industry devotes a great deal of efforts to synthesize novel compounds starting from cheaply available raw materials.
Several bi-, tri- and polycyclic derivatives, such as derivatives of decaline, bicyclo[2.2.2]octane, cedrene, caryophyllene and patchoulol for instance, have been proposed as perfuming ingredients in the recent past. Examples of these compounds include the following ones of formula ##STR11## known to develop a floral, woody and spicy odour [see e.g.: Swiss Pat. Nos. 547,850 and 557,870].
We have now discovered that the tricyclic derivatives of norbornane of formula I (a,b,c) possess useful organoleptic properties and that consequently they could be advantageously used in the perfume industry.
Compound of formula I (c), or 3-oxa-tricyclo[6.2.1.0.sup.2,7 ]undecan-4-one, has already been disclosed in the scientific literature [see Synth. Comm. 5, 347 (1957)], however its odorous properties have not been described, nor has its possible use as perfume ingredient ever been recognized.